The present invention relates to a stabilized switching voltage regulator comprising improved means for preventing overloads due to initial surge currents.
A conventional switching voltage regulator comprises an electronic switch such as a transistor and a comparator for comparing the output voltage of the regulator with a reference voltage and turning off the switch when the output voltage exceeds a predetermined value. The output voltage is developed across a filter capacitor.
In order to minimize interaction between multiple loads operated from the regulator, it has been known to provide a plurality of regulated outputs. This is because a power surge through one load will affect the other loads. However, a plurality of regulated outputs require a disproportionate increase in circuitry and cost. For this reason, it has been known to provide a preliminary filter, power oscillator and transformer between the switch and comparator. Where the transformer has a plurality of secondary windings and a rectifier and filter is provided for each winding, the comparator is connected to receive the output voltage of one of the filters. This generally aleviates the need for a regulated output for each load.
However, since the power oscillator is designed to have sufficient capacity to drive several high powered loads, it tends to produce excess voltage due to transient surges when the voltage is first applied to the regulator, especially if one or more of the loads is drawing full power. This may cause one or more of the loads to burn out in addition to the switch in the regulator.